ubifs: do_rename: Fix wrong space budget when target inode's nlink > 1

[ Upstream commit 25fce616a61fc2f1821e4a9ce212d0e064707093 ]

If target inode is a special file (eg. block/char device) with nlink
count greater than 1, the inode with ui->data will be re-written on
disk. However, UBIFS losts target inode's data_len while doing space
budget. Bad space budget may let make_reservation() return with -ENOSPC,
which could turn ubifs to read-only mode in do_writepage() process.

Fetch a reproducer in [Link].

Link: https://bugzilla.kernel.org/show_bug.cgi?id=216494
Fixes: 974763da840dbf ("UBIFS: add new flash file system")
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c
index 9a4f9563aceea759458f89869385a9ec43777bcc..332c0b02a0adeac6acd5d6aeb493fb2edfe2cb76 100644 (file)
--- a/fs/ubifs/dir.c
+++ b/fs/ubifs/dir.c
@@ -1296,6 +1296,8 @@ static int do_rename(struct inode *old_dir, struct dentry *old_dentry,
        if (unlink) {
                ubifs_assert(c, inode_is_locked(new_inode));
 
+               /* Budget for old inode's data when its nlink > 1. */
+               req.dirtied_ino_d = ALIGN(ubifs_inode(new_inode)->data_len, 8);
                err = ubifs_purge_xattrs(new_inode);
                if (err)
                        return err;